Which description correctly defines forced-draft and induced-draft operation?

Which description correctly defines forced-draft and induced-draft operation?

• A. Forced-draft pushes air into the furnace; induced-draft pulls air into the furnace.
• B. Forced-draft reduces draft; Induced-draft increases draft.
• C. Both increase combustion air to maximize flame temperature.
• D. Forced-draft pushes air into the furnace; induced-draft removes flue gases from the furnace to control draft and prevent backflow

Answer: (D)